A hybrid vehicle may be configured with an engine, a driveline disconnect clutch, a driveline integrated starter/generator DISG, and a dual mass flywheel positioned upstream of a transmission. The driveline configuration allows the engine and DISG to operate separately or together to propel the vehicle and store the vehicle's kinetic energy as electrical energy to propel the vehicle at a later time. The driveline configuration may provide versatility during a variety of driving conditions; however, the driveline configuration may have an increased inertia as compared to drivelines that only include an engine and transmission. The increased inertia is upstream of a transmission at a location where it may affect transmission shifting. In particular, the increased inertia may cause torque disturbances during transmission shifting.
The inventors herein have recognized the above-mentioned disadvantages and have developed a driveline method, comprising: in response to a transmission gear shift request, increasing transmission input shaft torque via an electric machine when electric machine speed is less than a threshold speed during a torque phase of the transmission gear shift; and decreasing transmission input shaft torque via slipping a driveline disconnect clutch during an inertia phase of the transmission gear shift.
By increasing torque supplied to a transmission input shaft via an electric machine when electric machine speed is less than a threshold speed during a torque phase of a gear shift, it may be possible to provide the technical result of improving smoothness of transmission shifting. Further, controlled slip may be applied to a driveline disconnect clutch to reduce torque applied to the transmission input shaft during an inertia phase of the gear shift to reduce driveline torque disturbances. Thus, by controlling torque applied to the transmission input shaft during a shift torque phase using a first torque control device and torque applied to the transmission input shaft during the shift's inertia phase using a second torque control device, it may be possible to improve shift smoothness in a way that is improved as compared to a method that attempts to improve transmission shifting via a single torque control device.
The present description may provide several advantages. In particular, the approach may improve driveline shift performance consistency. Further, the approach may reduce driveline torque disturbances. Further still, the approach may reduce degradation of driveline components by sharing torque control tasks amongst several torque control devices.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.